The embodiment relates to an actuating part of an electromagnetic switching device and an electromagnetic switching device including the same.
An electromagnetic switching device is an electric switch device serving as a connection converter to switch on/off a main circuit according to tiny variation of an input current. In the electromagnetic switching device, a contact point is moved by electromagnetic force so that current is applied or shut off.
FIG. 1 is a view illustrating an electromagnetic switching device according to the related art.
The electromagnetic switching device shown in FIG. 1 includes a housing 1, a fixed contact point 2 disposed at an upper portion in the housing 1, and a movable contact point 3 disposed under the fixed contact point 2 and repeatedly making contact with or separated from the fixed contact point 2.
The movable contact point 3 is coupled with a shaft 7 and moves up and down, and a movable core 6 is coupled with an outer peripheral surface of the shaft 7. A fixed core 4 is placed at an upper outer side of the movable core 6, and a coil 5 is disposed at outer sides of the movable core 6 and the fixed core 4.
Further, the fixed core 4 include an upper fixed core 4a and a lower core 4b. 
In addition, a return spring 9 is provided above the shaft 7.
An elastic member 8 is placed at a bottom surface of the housing 1 under the shaft 7 and the movable core 6.
Accordingly, if an electric current is applied to the coil 5, a driving force is applied to the movable core 6 so that the movable core 6 moves up together with the shaft 7 while pushing the shaft 7, thereby making the fixed contact point 2 contact with the movable contact point 3.
Meanwhile, if the current applied to the coil 5 is shut off, the shaft 7 moves down while being pressed by the return spring 9, and the descended shaft 7 and movable core 6 collide with the elastic member 8.
The elastic member 8 absorbs shock caused by collision between the shaft 7 and the movable core 6.
In the electromagnetic switching device of the related art having a structure as described above, when a current does not flow through the coil 5, a bottom end of the upper fixed core 4a is spaced apart from a top end of the movable core 6 by a distance A.
If the distance A is too long, an ascending force of the movable core becomes weak. If the distance A is too short, the movable core rapidly starts to move up with insufficient ascending force so that electric connection may not be achieved between the movable contact point and a driving contact point.
Accordingly, the distance A between the movable core 6 and the upper fixed core 4a must be appropriately maintained by a magnetic force generated from the coil.
However, if the internal temperature is increased due to the operation of the electromagnetic switching device, a generated magnetic force becomes weak so that there is a need to reduce the distance A between the fixed core and the movable core.